Expanding metallic tubulars downhole has become more common. Casing, slotted liners and screens have been expanded using a variety of techniques involving fluid pressure or a swage. The expansion of tubulars has to date excluded the use of composites. Composites offer advantages of light weight, good chemical and thermal resistance properties, and low cost. The problem with composites and other non-metallics is that they are too brittle to withstand significant expansions that would make them useful in a downhole application where expansion was contemplated when used in the finished form in which such tubular goods are currently available.
Attempts to use composites in the past were in applications that were not readily adapted for downhole use for a variety of reasons. A good example is U.S. Pat. No. 4,752,431. In this reference, the tubular is provided in a limp condition and unrolled. It comprises a sandwich of a cement layer between two layers that could be flexible plastic, rubber or canvas. When water or steam is circulated, the limp tubular assumes a cylindrical shape and the cement sets to provide rigidity. The application of this technology is for lining existing pipes such as those that cross under roads. Another stated advantage is that the limp pipe can follow the contour of the land and then be hardened when pressurized with water.
U.S. Pat. No. 5,634,743 uses a flexible lining that contains a curable synthetic resin in conjunction with a device advanced with the lining to apply ultrasonic energy to the leading end of the lining, as the lining is unfurled along the center of the pipe to be lined. Expansion is not contemplated in this process.
U.S. Pat. No. 5,925,409 shows a multi step procedure where a resin containing hydrogen is reacted with a polycarbodiimide to make a tube that can be inserted into another tube for the purpose of lining it. The inner tube is inflated to contact the outer tube and then cured in place with hot air or water, electricity or radiation. The liner tube is inflated as opposed to expanded. A similar concept is employed in German Application DE 3732694 A1.
U.S. Application U.S. 2001/0010781 A1 involves putting cables in a strip and then inflating a liner over the strip. The final step is to set the body with hot water in the liner or heat from cables that run through the body.
In WO 93/15131 a technique for lining sewer pipes and the like is illustrated where the liner is applied followed by the application of ultrasonic energy to liberate microencapsulated catalyst. Alternatively, iron oxide particles are incorporated in the resin and are caused to heat by applying electromagnetic energy. No expansion is contemplated. Related to this technique are U.S. Pat. Nos. 4,064,211; 4,680,066; 4,770,562.
Elastic Memory Composites and their ability to be deformed on heating and to hold the deformed shape on subsequent cooling, have been described in a paper published by IEEE in 2001 entitled Developments in Elastic Memory Composite Materials for Spacecraft Deployable Structures. These materials resume their original shape when reheated. More recently, R&D Magazine published in the July 2002 issue on page 13, an article describing the ability of a composite tube to fix stress cracks that form by liberation of an encapsulated compound as a result of the crack formation. Shape memory materials and some of their uses are described in an article by Liang, Rogers and Malafeew entitled Investigation of Shape Memory Polymers and their Hybrid Composites which appeared in the April 1997 edition of the Journal of Intelligent Materials Systems and Structures. Also of interest is American Institute of Aeronautics and Astronautics paper 2001-1418 entitled Some Micromechanics Considerations of the Folding of Rigidizable Composite Materials.
The object of this invention is to employ non-traditional materials for well tubulars by taking advantage of their properties to allow the tubular to be rapidly deployed into a wellbore and then expanded in place. The expansion can trigger a reaction that will harden the tubular in place to allow it to function downhole. Alternatively, the reaction can be otherwise triggered and the tubular expanded. Additionally, healing agents can also be encapsulated in the tubular to heal subsequently forming cracks that may develop during the service life of the expanded tubular. While composites that are flexible until a reaction occurs are envisioned as the preferred material, other materials are envisioned that preferably can be coiled with the catalyst encapsulated and that become rigid on expansion with the liberation of the catalyst. These and other advantages of the present invention will become more apparent to those skilled in the art from a review of the description of the preferred embodiment and claims, below.